3-aminocarbazole compound, pharmaceutical composition containing it and preparation method therefor

ABSTRACT

The present invention relates to novel benzoyl derivatives of 3-aminocarbazole, to a pharmaceutical composition containing them, to a method for preparing them and to the use of such compounds for the production of a drug that is useful in the treatment or prevention of disturbances associated with the production of prostaglandin E 2  (PGE 2 ), for instance inflammatory processes, pain, fever, tumours, Alzheimer&#39;s disease and atherosclerosis.

FIELD OF THE INVENTION

The present invention relates to novel 3-aminocarbazole compounds, to apharmaceutical composition containing them, to a method for preparingthem, and to the use of such compounds for the production of a drug thatis useful in the treatment of disturbances associated with theproduction of prostaglandin E₂ (PGE₂), for instance inflammatoryprocesses, pain, fever, tumours, Alzheimer's disease andatherosclerosis.

More particularly, the present invention relates to novel benzoylderivatives of 3-aminocarbazole that are useful for treating orpreventing disturbances associated with the production of prostaglandinE₂ (PGE₂), for instance inflammatory processes, pain, fever, tumours,Alzheimer's disease and atherosclerosis.

PRIOR ART

The value of the prostaglandin E₂ (PGE₂) arises from the role that theyplay as bioregulators, together with other prostanoids producedmetabolically from arachidonic acid, and as inflammation mediators.

Prostanoids are a class of compounds including prostaglandins,thromboxanes and prostacyclins. Prostanoids are lipid mediators that actas local hormones on the cells adjacent to the site of their release.Prostanoids are mainly produced from arachidonic acid bycyclooxygenase-activated enzymatic oxidation. Cyclooxygenases(prostaglandin G/H synthases) catalyse the sequential formation of PGG₂and PGH₂ from arachidonic acid. PGH₂ is then converted by means ofspecific enzymes into various prostanoids. The prostaglandin D₂ (PGD₂),prostaglandin E₂ (PGE₂), prostaglandin F_(2α) (PGF_(2α)), prostaglandinI₂ (PGI₂) and thromboxane A₂ (TXA₂) are formed in this way.

With the exception of seminal fluid, prostanoids are not accumulated.Following various stimuli (inflammatory, immunological, hormonal,ultraviolet light, tumoral agents and also mechanical agitation), theyare synthesized and released into the extracellular space, from wherethey pass into the plasma, the urine and other biological fluids.

Prostanoids play an important role in the defence mechanisms of thefunctioning of organs and in the integrity of the body. This isdemonstrated by the cytoprotective function in the gastrointestinaltract, by the regulation of the renal function and of capillarycirculation, by the regulation of platelet aggregation and bloodclotting, the involvement in the differentiation of immune cells and inwound repair, bone metabolism and ovulation.

In particular, the vasoprotective action of the PGI₂, which areessential for maintaining vascular tonus and for preventingthromboembolism and atherosclerosis at the endothelial level, and theanti-inflammatory and antiproliferative action of the PGD₂, themetabolite of which, 15d-PGJ₂, is capable of exerting anti-inflammatoryeffects by means of activation of the PPARγ (peroxisomeproliferator-activated receptor-gamma) nuclear receptors (Inoue et al.,2000, “Feedback control of cyclooxygenase-2 expression throughPPARgamma” J. Biol. Chem. 2000, 275(36): 28028-28032), should beunderlined.

Prostanoids are thus bioregulators, but also important mediators ofinflammation and of other pathologies.

In particular, the PGE₂ are abundant at the sites of inflammation andare responsible for various pathological aspects of acute and chronicinflammation, for instance oedema, the formation of erythemas,inflammatory pain, articular inflammation and fever. In point of fact,the PGE₂ represent potent pro-inflammatory and algogenic agents.Anti-PGE₂ antibodies have anti-inflammatory activity and animals lackingPGE₂ receptors show a reduced response to inflammatory stimuli(Portanova et al., “Selective neutralization of prostaglandin E2 blocksinflammation, hyperalgesia, and interleukin 6 production in vivo”, J.Exp. Med. 1996, 184(3): 883; Ueno et al., “Major roles of prostanoidreceptors IP and EP(3) in endotoxin-induced enhancement of painperception” Biochem. Pharmacol. 2001, 62(2): 157-160) and no febrileresponse to pyrogenic stimuli (Ushikubi et al., “Impaired febrileresponse in mice lacking the prostaglandin E receptor subtype EP3”Nature 1998, 395:281-284).

The non-steroidal anti-inflammatory drugs (NSAIDs) and selective COX-2drugs currently in use reduce the inflammation-related symptoms by meansof the non-selective inhibition of the production of eicosanoids (PGE₂,PGD₂, PGF_(2α), PGI₂ and TXA₂) on account of their inhibitory action onthe cyclooxygenases 1 and 2 (Fitzgerald and Patrono, 2001).

In particular, the selective COX-2 drugs currently marketed have reducedgastrointestinal toxicity when compared with conventional non-steroidalanti-inflammatory drugs (NSAIDs). However, the said selective COX-2drugs reduce the production of vascular prostacyclin (PGI₂, which isproduced predominantly from COX-2), altering the normal equilibriumbetween the prothrombotic and antithrombotic eicosanoids in favour ofthe prothrombotic (TXA₂, which is produced predominantly from COX-1),and give rise to an increased risk of thrombotic-cardiovascular events(S. Malhotra, MD, DM; N. Shafiq, MD; P. Pandhi, MD Medscape GeneralMedicine 6(1), 2004; D. Mukherjee and E. J. Topol Cardiovascular riskand COX-2 inhibitors, Arthritis Res. Ther. 2003, 5:8-11-2002).

Various 3-aminocarbazole compounds have been studied for their abilityto selectively bind to the human Y5 receptor and to modulate itsactivity. This ability makes them useful in the treatment of appetiteand metabolic disorders, for instance obesity, bulimia nervosa, anorexianervosa, sleep disturbances, morphine dependency and epileptic attacks(WO 01/07409 A1, WO 02/051806, WO 02/096902 and U.S. Pat. No.6,399,631).

Patent application WO 2006/122 680 describes the use of a number of3-aminocarbazole compounds for treating disturbances related to theproduction of prostaglandin E₂ (PGE₂). In addition, patent applicationWO 2007/014 687 describes a number of novel 3-aminocarbazole compoundsand their use for treating disturbances related to the production ofprostaglandin E₂ (PGE₂).

SUMMARY OF THE INVENTION

It has now been found, surprisingly, that certain novel 3-aminocarbazolecompounds, besides being capable of selectively inhibiting theproduction of prostaglandin E₂ (PGE₂), have shown, surprisingly,improved bioavailability and pharmacokinetic properties.

These compounds are capable of reducing the production of PGE₂ and arethus active in all the pathological conditions in which PGE₂ acts as amediator, for instance inflammatory processes, pain, fever, tumours,Alzheimer's disease and atherosclerosis.

In addition, these compounds have shown, surprisingly, high metabolicstability, high absorption in vitro and high bioavailability.

Typical examples of such inflammatory processes are oedema, erythema,articular inflammation, rheumatoid arthritis and arthrosis.

Typical examples of such tumours are colorectal and pulmonary carcinomaand adenocarcinoma.

The compounds of the present invention selectively inhibit the synthesisof PGE₂. This selectivity has the advantage of inhibiting a potentmediator of inflammation, pain and fever, while leaving unaltered theproduction of the other prostanoids produced simultaneously in thearachidonic acid cascade, such as PGF_(2α), TXA₂, PGI₂ and PGD₂. All thedefence mechanisms of the functioning of organs and of the integrity ofthe body that are typical of the activity of the other prostanoids thusremain unchanged.

Similarly to conventional non-steroidal anti-inflammatory drugs, thecompounds of the present invention have anti-inflammatory, antipyreticand analgesic properties, and are thus active in pathologies such asinflammation, pain, fever, rheumatoid arthritis and arthrosis. Inaddition, since the involvement of PGE₂ in tumours, Alzheimer's diseaseand atherosclerosis is known in the literature, the compounds of thepresent invention also have applications in the prevention and treatmentof these pathologies.

Advantageously, these compounds however show few side effects whencompared with NSAIDs and selective COX-2 drugs, which, by inhibitingcyclooxygenases, do not discriminate between the prostanoids.

In particular, these compounds are useful in both the treatment and theprevention of inflammatory processes.

In particular, the compounds of the present invention show reducedgastrointestinal, renal and vascular toxicity.

DETAILED DESCRIPTION OF THE INVENTION

In a first aspect, the present invention relates to a 3-aminocarbazolecompound having the general formula (I) below:

in which

R1 is a halogen atom, a methyl group or a trihalomethyl group, a nitrogroup, a cyano group or a triflate group, and

R2 is a linear or branched hydroxyalkyl group comprising from 1 to 8carbon atoms or a linear or branched carbonylalkyl group comprising from1 to 8 carbon atoms, or

a pharmaceutically acceptable salt thereof, a polymorphic crystal formthereof, a stereoisomer thereof or an enantiomer thereof.

In particular, the present invention relates to 3-aminocarbazolecompounds of general formula (I) in which R1 is a fluorine or chlorineatom, or a trifluoromethyl or trichloromethyl group, and R2 is a linearor branched hydroxyalkyl group comprising from 1 to 6 carbon atoms or alinear or branched carbonylalkyl group comprising from 1 to 4 carbonatoms.

For the purposes of the present invention, the term “hydroxyalkyl” meansan alkyl group comprising from 1 to 3 hydroxyl groups (—OH) bonded toone or more carbon atoms, and the term “carbonylalkyl” means an alkylgroup comprising from 1 to 3 oxy groups (═O) bonded to one or morecarbon atoms.

According to the preferred aspect, the present invention relates to3-aminocarbazole compounds of general formula (I) in which R1 and R2have the meaning given in Table 1 below.

TABLE 1 Compound R1 R2 1 CF₃ CH₂CH₂OH 2 CF₃ CH₂C(CH₃)₂OH 3 CF₃CH₂CH₂C(CH₃)₂OH 4 CF₃ CH₂COCH₃ 5 Cl CH₂CH₂OH 6 Cl CH₂CH₂C(CH₃)₂OH

Formula (I) described previously comprises compounds in which the phenylgroup bears, besides R1, one or more substituents such as, for example,a halogen atom, an alkyl group comprising from 1 to 3 carbon atoms, atrifluoromethyl group, a nitro group, a triflate group (CF₃SO₃—), analkylcarboxyl group comprising from 1 to 3 carbon atoms(—(CH₂)_(n)COOH), an amide group (—CONH₂), a methylsulfoxy group(—SO₂CH₃), an N-methylsulfonamide group —SO₂NHCH₃ or amethanesulfonamide group NHSO₂CH₃.

As is known to those skilled in the art, the pharmaceutically acceptablesalts of the compounds of general formula (I) may be base-additionsalts. Examples of suitable pharmaceutically acceptable bases are alkalimetals and alkaline-earth metals such as Na⁺, K⁺, Mg⁺⁺, Ca⁺⁺ and organicbases such as tromethamine, choline and lysine.

The compounds of general formula (I) according to the present inventionmay have more than one crystal structure or form, or may be in amorphousform. The compounds that have this characteristic are commonly referredto as polymorphs. Different polymorphs of this compound may exhibitdifferent chemical, physical and spectroscopic properties.

In addition, in the case of certain substituents, the compounds ofgeneral formula (I) according to the present invention may have one ormore asymmetric carbon atoms and may thus be in the form ofstereoisomers and enantiomers.

Thus, the compounds of the present invention also include thepharmaceutically acceptable salts, the polymorphic crystal forms, thestereoisomers and the enantiomers of a compound represented by formula(I) described in the claims.

In a second aspect, the present invention relates to a pharmaceuticalcomposition characterized in that it comprises a therapeuticallyeffective dose of a 3-aminocarbazole compound having the abovementionedgeneral formula (I) or a pharmaceutically acceptable salt thereoftogether with at least one pharmaceutically acceptable inert vehicle.

Preferably, the pharmaceutical compositions of the present invention areprepared in suitable dosage forms.

Examples of suitable dosage forms are tablets, capsules, coated tablets,granules, and solutions and syrups for oral administration; creams,ointments and antiseptic plasters for topical administration;suppositories for rectal administration and sterile solutions foradministration by injection, or aerosol or ophthalmic administration.

Advantageously, these dosage forms are formulated so as to ensure acontrolled release over time of a compound of the abovementioned generalformula (I) or of a pharmaceutically acceptable salt thereof.Specifically, depending on the type of therapy, the required releasetime may be very short, normal or long.

The dosage forms may also contain other conventional ingredients, forinstance; preserving agents, stabilizers, surfactants, buffers, saltsfor regulating the osmotic pressure, emulsifiers, sweeteners, dyes,flavourings and the like.

In addition, when required for particular therapies, the pharmaceuticalcomposition of the present invention may also contain otherpharmacologically active ingredients whose simultaneous administrationis useful.

Advantageously, the pharmaceutical composition of the present inventionmay contain a prodrug of a compound of formula (I). The prodrug of acompound of formula (I) is a substance in substantially inactive formwhich, when administered to a living being, is metabolized into acompound of formula (I). As is known to those skilled in the art, theprodrug of the compounds of general formula (I) may be ester derivativesobtained by reacting the hydroxy group of R2 with an acid, such as amonocarboxylic acid, a bicarboxylic acid, a fatty acid, an aminoacid, an(alkyl)phosphoric acid, or an (alkyl)tiophosphoric acid. Examples ofsuitable prodrugs are acetyl ester, propionyl ester, succinyl ester,stearate ester, palmitate ester, glycine ester, leucine ester, lysineester, phosphate ester, methylphosphate ester, methyltiophosphate ester,and phosphonate ester. Useful examples of suitable prodrugs aredescribed, for example, in Stella V. J. et al, “Prodrug strategies toovercome poor water solubility”, Advance Drug Delivery Reviews 59 (2007)677-694. The composition of the present invention may also include thepharmaceutically acceptable salts, polymorphic crystal forms,stereoisomers and enantiomers of the prodrug of a compound representedby formula (I) described in the claims.

The amount of the compound of the present invention in thepharmaceutical composition may vary within a wide range as a function ofknown factors, for instance the type of disease to be treated, theseverity of the disease, the body weight of the patient, the dosageform, the selected route of administration, the number of dailyadministrations and the efficacy of the selected compound. However, theoptimum amount may be readily and routinely determined by a personskilled in the art.

Typically, the amount of compound of the present invention in thepharmaceutical composition will be such that it ensures a level ofadministration of between 0.0001 and 100 mg/kg/day and even morepreferably between 0.01 and 10 mg/kg/day.

The dosage forms of the pharmaceutical composition of the presentinvention may be prepared according to techniques that are well known topharmaceutical chemists, including mixing, granulation, tabletting,dissolution, sterilization and the like.

In a third aspect, the present invention relates to a method fortreating or preventing inflammatory processes, pain, fever, tumours,Alzheimer's disease and atherosclerosis in mammals, comprising theadministration of a therapeutically effective amount of a3-aminocarbazole compound having the abovementioned general formula (I),a pharmaceutically acceptable salt thereof, a polymorphic crystal formthereof, a stereoisomer thereof or an enantiomer thereof, to a person inneed thereof.

Preferably, the inflammatory process is chosen from the group comprisingoedema, erythema, articular inflammation, rheumatoid arthritis andarthrosis, and the tumour is chosen from the group comprising colorectalor pulmonary carcinoma and adenocarcinoma.

The 3-aminocarbazoles having the abovementioned general formula (I) maybe prepared according to known methods, for instance by reacting anacid, or a reactive derivative thereof, with the selected amine (patentapplication WO 02/096902 A1, WO 02/051806, J. Med. Chem. 2002 vol. 45,pp. 3509-3523). Typical examples of reactive derivatives are acylhalides, anhydrides or esters.

In a fourth aspect, the present invention thus relates to a method forpreparing a 3-aminocarbazole having the abovementioned general formula(I), characterized in that it comprises the following stages:

a) reaction of an amine of formula (II)

in which R2 has the meaning given previously,with a compound of formula (III)

in which R1 has the meaning given previously, andZ is chosen from the group comprising Cl, Br, OH, OR and OC(O)R, inwhich R is a linear or branched alkyl having from 1 to 6 carbon atoms,to give a 3-aminocarbazole compound of formula (I)

in which R1 and R2 have the meanings given previously, andb) optional formation of a pharmaceutically acceptable salt, apolymorphic crystal form, a stereoisomer or an enantiomer of thecompound of formula (I) thus obtained.

Typically, step (a) is performed in the presence of a suitable diluentat a temperature within the range between 0 and 140° C., for a timewithin the range between 0.5 and 24 hours. Preferably, the reactiontemperature is within the range between 15 and 40° C. Advantageously,the reaction time ranges from 2 to 18 hours.

Preferably, the diluent is aprotic, polar or apolar. Even morepreferably, it is a polar aprotic diluent. Examples of suitable polaraprotic diluents are dimethylformamide and dichloromethane.

In the embodiment in which Z is Cl or Br, the reaction is advantageouslyperformed in the presence of a suitable organic or inorganic acidacceptor. Examples of suitable organic acceptors arediisopropylethylenediamine, triethyleneamine, pyridine anddimethylaminopyridine. Examples of suitable inorganic acceptors arealkali metal carbonates or bicarbonates.

In the embodiment in which Z is OH, the reaction is preferably performedin the presence of a suitable coupling agent, for instancedicyclohexylcarbodiimide (also supported on polystyrene resin) orcarbonyldiimidazole.

The examples that follow are given to illustrate the invention ingreater detail without, however, limiting it.

EXAMPLE 1 Preparation of Compound 1 R1=CF₃, R2=CH₂CH₂OH a)2-(3-nitro-9H-carbazol-)ethanol

To a solution of 2-(9H-carbazol-9-yl)ethanol (25 g; 0.12 mol) in glacialacetic acid (374 ml) was added dropwise over 30 minutes a solutioncontaining nitric acid (6.8 ml; 0.17 mol) in glacial acetic acid (20ml), with vigorous stirring. Five minutes after completion of theaddition, a green precipitate separated out. The reaction mixture waspoured slowly into H₂O and ice (1 L), stirred for 1 hour, filtered andfinally washed with H₂O. The solid separated out was taken up first inH₂O (500 ml) and then with 10% sodium carbonate solution to obtain a pHof 7, and finally filtered off. The solid obtained was crystallized froma solution of acetone/absolute ethanol (1:1) to give 20 g of2-(3-nitro-9H-carbazol-)ethanol

¹H NMR (300 MHz, DMSO-d₆) δ 9.16 (d, J=2.34 Hz, 1H), 8.40 (d, J=7.75 Hz,1H), 8.33 (dd, J=2.34, 9.21 Hz, 1H), 7.79 (d, J=9.06 Hz, 1H), 7.73 (d,J=8.33 Hz, 1H), 7.57 (ddd, J=1.24, 7.13, 8.29 Hz, 1H), 7.33 (ddd,J=0.95, 7.13, 7.86 Hz, 1H), 4.89 (t, J=5.90 Hz, 1H), 4.54 (t, J=5.41 Hz,2H), 3.82 (q, J=5.41 Hz, 2H).

b) 2-(3-amino-9H-carbazol-)ethanol hydrochloride

The product obtained as described in the preceding step a) (10 g; 0.04mol) was dissolved in tetrahydrofuran (550 ml). Stannous chloridedihydrate (87 g; 0.4 mol) was then added. The mixture thus obtained wasrefluxed for 16 hours.

The reaction mixture was allowed to cool to room temperature and thesolvent was then removed under reduced pressure. The residue was takenup in H₂O and dichloromethane, and stirred vigorously. The pH wasbrought to 7.5 by adding saturated sodium bicarbonate solution, themixture was filtered through Celite and the filtrate transferred into aseparating funnel. The organic phase was separated out and dried overNa₂SO₄. The solvent was removed by evaporation under reduced pressureand the residue thus obtained (9 g) was dissolved in ethanol andconverted into the corresponding hydrochloride by adding ethanolic 5 Mhydrogen chloride solution. The precipitated solid was filtered off togive 2-(3-amino-9H-carbazol-)ethanol hydrochloride (9 g).

¹H NMR (300 MHz, DMSO-d₆) δ 10.41 (broad s, 3H), 8.17 (d, J=7.76 Hz,1H), 8.12 (d, J=1.98 Hz, 1H), 7.73 (d, J=8.75 Hz, 1H), 7.66 (d, J=8.26Hz, 1H), 7.38-7.56 (m, 2H), 7.23 (t, J=7.27 Hz, 1H), 4.70 (broad s, 1H),4.47 (t, J=5.53 Hz, 2H), 3.78 (t, J=5.45 Hz, 2H).

c) N-[9-(2-hydroxyethyl)-9H-carbazol-3-yl]-2-(trifluoromethyl)benzamide

The product obtained as described in the preceding step b) (26 g; 0.1mol) was suspended in dichloromethane (300 ml). Triethylamine (28 ml;0.2 mol) and 2-trifluoromethylbenzoyl chloride (15.6 ml; 0.11 mol) werethen added to the solution. The mixture thus obtained was stirred atroom temperature for 16 hours.

The solvent was evaporated off under reduced pressure, the residue wastaken up in 2N NaOH solution (200 ml), and the resulting solution wasrefluxed for 2 hours. The suspension thus obtained was poured into waterand the product was filtered off, dried and crystallized from anisopropyl ether/isopropanol mixture (1:1).

N-[9-(2-Hydroxyethyl)-9H-carbazol-3-yl]-2-(trifluoromethyl)benzamide (24g) was thus obtained.

m.p.: 176-177° C.

Elemental analysis for C₂₂H₁₇F₃N₂O₂

C H N Found % 66.14 4.06 6.85 Calculated % 66.33 4.30 7.03

¹H NMR (300 MHz, DMSO-d₆) δ 10.52 (s, 1H), 8.50 (d, J=1.75 Hz, 1H), 8.08(d, J=7.31 Hz, 1H), 7.54-7.93 (m, 7H), 7.44 (t, J=7.02 Hz, 1H), 7.18 (t,J=7.45 Hz, 1H), 4.85 (t, J=5.45 Hz, 1H), 4.43 (t, J=5.70 Hz, 2H), 3.79(q, J=5.75 Hz, 2H).

EXAMPLE 2 Preparation of Compound 2 R1=CF₃, R2=CH₂C(CH₃)₂OH a)1-(9H-carbazol-9-yl)-2-methylpropan-2-ol

To a solution containing carbazole (20 g; 0.12 mol) in DMSO (300 ml) wasadded 50% sodium hydroxide solution (300 ml), benzyltrimethylammoniumchloride (5.5 g; 0.024 mol) and, dropwise, 2-chloro-2-methylpropan-2-ol(39.1 g; 0.36 mol). The mixture thus obtained was stirred at roomtemperature for 16 hours.

The mixture was poured into H₂O and ice (3 L), stirred for 1 hour andfiltered, and the solid obtained was crystallized from a hexane/ethylacetate mixture (9:1) to give 1-(9H-carbazol-9-yl)-2-methylpropan-2-ol(15 g).

¹H NMR (300 MHz, DMSO-d₆) δ 8.07-8.15 (m, 2H), 7.68 (d, J=8.33 Hz, 2H),7.40 (ddd, J=1.24, 7.13, 8.29 Hz, 2H), 7.13-7.20 (m, 2H), 4.64 (s, 1H),4.26 (s, 2H), 1.21 (s, 6H).

b) 1-(3-nitro-9H-carbazol-)-2-methylpropan-2-ol

To a solution of the product obtained as described in the preceding stepa) (21 g; 0.088 mol) in glacial acetic acid (400 ml) was added dropwiseover 30 minutes a solution containing nitric acid (5 ml; 0.123 mol) inglacial acetic acid (15 ml; 0.263 mol) with vigorous stirring. 5 minutesafter completion of the addition, a green precipitate separated out. Thereaction mixture was poured slowly into H₂O and ice (1 L), stirred for 1hour, filtered and finally washed with H₂O. The solid separated out wastaken up first in H₂O (500 ml) and then in 10% sodium carbonate solutionuntil a pH of 7 was obtained, and finally filtered off.

The solid obtained was crystallized from an ethyl acetate/ethanolmixture (8:2) to give 1-(3-nitro-9H-carbazol-)-2-methylpropan-2-ol (19g).

¹H NMR (300 MHz, DMSO-d₆) δ 9.15 (d, J=2.05 Hz, 1H), 8.38 (d, J=7.31 Hz,1H), 8.30 (dd, J=2.48, 9.21 Hz, 1H), 7.87 (d, J=9.06 Hz, 1H), 7.81 (d,J=8.48 Hz, 1H), 7.54 (ddd, J=1.17, 7.16, 8.33 Hz, 1H), 7.31 (td, J=0.88,7.60 Hz, 1H), 4.73 (s, 1H), 4.37 (s, 2H), 1.21 (s, 6H).

c) 1-(3-amino-9H-carbazol-)-2-methylpropan-2-ol hydrochloride

The product obtained as described in the preceding step b) (7.9 g; 0.028mol) was dissolved in tetrahydrofuran (350 ml). Stannous chloridedihydrate (62.8 g; 0.28 mol) was then added. The mixture thus obtainedwas refluxed for 16 hours.

The reaction mixture was allowed to cool to room temperature and thesolvent was then removed under reduced pressure. The residue was takenup in H₂O and dichloromethane, and subjected to vigorous stirring. ThepH was brought to 7.5 by adding saturated sodium bicarbonate solution,the mixture was filtered through Celite and the filtrate transferredinto a separating funnel. The organic phase was separated out and driedover Na₂SO₄. The solvent was removed by evaporation under reducedpressure and the residue thus obtained (9 g) was dissolved in ethanoland converted into the corresponding hydrochloride by adding ethanolic 5M hydrogen chloride solution. The solid obtained was crystallized froman isopropanol/water mixture (8:2) to give1-(3-amino-9H-carbazol-)-2-methylpropan-2-ol hydrochloride (6 g).

¹H NMR (300 MHz, DMSO-d₆) δ 10.32 (broad s, 3H), 8.16 (d, J=7.60 Hz,1H), 8.10 (d, J=2.31 Hz, 1H), 7.81 (d, J=8.92 Hz, 1H), 7.74 (d, J=8.26Hz, 1H), 7.47 (ddd, J=0.99, 7.10, 8.42 Hz, 1H), 7.42 (dd, J=2.15, 8.75Hz, 1H), 7.22 (t, J=7.43 Hz, 1H), 4.70 (broad s, 1H), 4.30 (s, 2H), 1.20(s, 6H).

d)N-[9-(2-hydroxy-2-methylpropyl)-9H-carbazol-3-yl]-2-(trifluoro-methyl)benzamide

The product obtained as described in the preceding step c) (3.3 g; 0.011mol) was suspended in dichloromethane (30 ml). Triethylamine (3 ml;0.022 mol) and 2-trifluoromethylbenzoyl chloride (1.7 ml; 0.012 mol)were then added to the solution. The mixture thus obtained was stirredat room temperature for 16 hours.

The solvent was evaporated off under reduced pressure, the residue wastaken up in 2N NaOH solution (20 ml) and the resulting solution wasrefluxed for 2 hours. The suspension thus obtained was poured into waterand the product was filtered off, dried and crystallized from anisopropyl ether/isopropanol mixture (1:1).

N-[9-Hydroxy-2-methylpropyl)-9H-carbazol-3-yl]-2-(trifluoromethyl)-benzamide(2.7 g) was thus obtained.

m.p.: 179-181° C.

Elemental analysis for C₂₄H₂₁F₃N₂O₂

C H N Found % 67.51 4.82 6.52 Calculated % 67.60 4.96 6.57

¹H NMR (300 MHz, DMSO-d₆) δ 10.50 (s, 1H), 8.49 (s, 1H), 8.06 (d, J=7.93Hz, 1H), 7.56-7.92 (m, 7H), 7.42 (t, J=7.76 Hz, 1H), 7.17 (t, J=7.43 Hz,1H), 4.65 (s, 1H), 4.26 (s, 2H), 1.21 (s, 6H).

EXAMPLE 3 Preparation of Compound 3 R1=CF₃, R2=CH₂CH₂C(CH₃)₂OH a) Ethyl3-(9H-carbazol-9-yl)propanoate

To a solution containing carbazole (20 g; 0.12 mol) in DMF (130 ml) wasadded portionwise sodium hydride (50% suspension) (6.7 g; 0.14 mol); thesuspension thus obtained was stirred at room temperature for 30 minutesand then heated to 60° C. A solution containing ethyl 3-bromopropanoate(17.9 ml; 0.14 mol) in DMF (20 ml) was added dropwise and the mixturewas stirred for 16 hours.

The mixture was poured into H₂O (0.5 L) and filtered. The solid obtainedwas purified by flash chromatography on silica, using as eluent ahexane/ethyl acetate mixture (8:2) to give 16 g of ethyl3-(9H-carbazol-9-yl)propanoate, which product was used in the subsequentreaction without further purification.

b) 4-(9H-carbazol-9-yl)-2-methylbutan-2-ol

To a solution of the product obtained in the preceding step a) (15.2 g;0.057 mol) in tetrahydrofuran (200 ml) was added a 3M solution ofmethylmagnesium iodide in diethyl ether (57 ml; 0.171 mol). The mixturethus obtained was stirred at room temperature for 16 hours. 1M NH₄Clsolution (500 ml) was then added to the mixture. The resulting mixturewas transferred into a separating funnel and extracted with ethylacetate. The organic phase was dried over Na₂SO₄ and the solventevaporated off under reduced pressure. The residue obtained wascrystallized from a hexane/ethyl acetate mixture (8:2) to give4-(9H-carbazol-9-yl)-2-methylbutan-2-ol (9 g), which product was used inthe subsequent reaction without further purification.

c) 2-methyl-4-(3-nitro-9H-carbazol-)butan-2-ol

The product obtained in the preceding step b) (7.2 g; 0.028 mol) wasreacted by working in a manner similar to that described in Example 1a).The product obtained was crystallized from ethyl acetate to give2-methyl-4-(3-nitro-9H-carbazol-)butan-2-ol (6 g).

¹H NMR (300 MHz, DMSO-d₆) δ 9.17 (d, J=2.34 Hz, 1H), 8.41 (d, J=7.60 Hz,1H), 8.36 (dd, J=2.34, 9.35 Hz, 1H), 7.73 (d, J=9.35 Hz, 1H), 7.66-7.71(m, 1H), 7.56-7.64 (m, 1H), 7.31-7.38 (m, 1H), 4.62 (s, 1H), 4.48-4.58(m, 2H), 1.79-1.89 (m, 2H), 1.24 (s, 6H).

d) 4-(3-amino-9H-carbazol-)-2-methylbutan-2-ol hydrochloride

To a suspension of the product obtained in the preceding step c) (5.9 g;0.020 mol) in 95° ethanol (80 ml) was added 10% Pd/C (0.5 g; 0.0005 mol)and the mixture was subjected to hydrogenation in a Parr hydrogenator(30 psi) for 4 hours. The reaction mixture was filtered, the solutionwas evaporated under reduced pressure and the product obtained wasdissolved in ethyl acetate and converted into the correspondinghydrochloride by adding ethanolic 5M hydrogen chloride solution. Thesolid thus obtained was crystallized from an isopropyl ether/isopropanolmixture (1:1) to give 4-(3-amino-9H-carbazol-)-2-methylbutan-2-olhydrochloride (5.5 g).

¹H NMR (300 MHz, DMSO-d₆) δ 10.34 (broad s, 3H), 8.19 (d, J=7.60 Hz,1H), 8.13 (d, J=1.98 Hz, 1H), 7.68 (d, J=8.92 Hz, 1H), 7.62 (d, J=8.20Hz, 1H), 7.44-7.58 (m, 2H), 7.25 (t, J=6.94 Hz, 1H), 4.08-4.83 (m, 3H),1.73-1.88 (m, 2H), 1.23 (s, 6H).

e)N-[9-(3-hydroxy-3-methylbutyl)-9H-carbazol-3-yl]-2-trifluoromethyl-benzamide

The product obtained as described in the preceding step d) (3.9 g; 0.013mol) was reacted by working in a manner similar to that described inExample 1c).

The solid obtained was crystallized from ethanol to giveN-[9-(3-hydroxy-3-methylbutyl)-9H-carbazol-3-yl]-2-(trifluoromethyl)benzamide(2.3 g).

m.p.: 188-189° C.

Elemental analysis for C₂₅H₂₃F₃N₂O₂

C H N Found % 67.75 5.31 6.23 Calculated % 68.17 5.26 6.36

¹H NMR (300 MHz, DMSO-d₆) δ 10.53 (s, 1H), 8.52 (d, J=1.98 Hz, 1H), 8.10(d, J=7.60 Hz, 1H), 7.68-7.90 (m, 4H), 7.66 (dd, J=2.00, 8.70 Hz, 1H),7.52-7.59 (m, 2H), 7.47 (t, J=7.10 Hz, 1H), 7.19 (t, J=7.43 Hz, 1H),4.55 (s, 1H), 4.38-4.51 (m, 2H), 1.71-1.91 (m, 2H), 1.23 (s, 6H).

EXAMPLE 4 Preparation of Compound 4 R1=CF₃, R2=CH₂COCH₃ a) Ethyl9H-carbazol-9-ylacetate

To a solution containing carbazole (20 g; 0.12 mol) in DMF (130 ml) wasadded portionwise sodium hydride (50% suspension) (6.9 g; 0.14 mol); thesuspension thus obtained was stirred at room temperature for 30 minutesand then heated to 60° C. A solution containing ethyl 2-bromoacetate (24g; 0.14 mol) in DMF (20 ml) was added dropwise, and the resultingmixture was stirred for 16 hours. The mixture was poured into H₂O (0.5L) and filtered, and the solid obtained was crystallized from hexane togive ethyl 9H-carbazol-9-ylacetate (20 g).

¹H NMR (300 MHz, DMSO-d₆) δ 8.15 (d, J=7.60 Hz, 2H), 7.54 (d, J=8.20 Hz,2H), 7.43 (td, J=1.02, 7.67 Hz, 2H), 7.17-7.27 (m, 2H), 5.33 (s, 2H),4.14 (q, J=7.02 Hz, 2H), 1.20 (t, J=7.16 Hz, 3H).

b) 1-(9H-carbazol-9-yl)acetone

To a solution of the product obtained in the preceding step a) (14.1 g;0.056 mol) in tetrahydrofuran (130 ml) was added a 3M solution ofmethylmagnesium iodide in diethyl ether (28 ml; 0.084 mol). The mixturethus obtained was stirred at room temperature for 16 hours. 1M NH₄Clsolution (100 ml) was then added to the mixture. The resulting mixturewas transferred into a separating funnel and extracted with ethylacetate. The organic phase was dried over Na₂SO₄ and the solvent wasevaporated off under reduced pressure. The residue obtained was purifiedby flash chromatography on silica, using as eluent a hexane/ethylacetate mixture (95:5) to give 1-(9H-carbazol-9-yl)acetone (8 g), whichproduct was used without further purification in the subsequentreaction.

¹H NMR (300 MHz, DMSO-d₆) δ 8.15 (d, J=7.89 Hz, 2H), 7.49 (d, J=8.20 Hz,2H), 7.41 (ddd, J=1.10, 7.00, 8.20 Hz, 2H), 7.21 (ddd, J=1.10, 7.00,7.89 Hz, 2H), 5.39 (s, 2H), 2.24 (s, 3H).

c) 1-(3-nitro-9H-carbazol-)acetone

The product obtained in the preceding step b) (5 g; 0.022 mol) wasreacted by working in a manner similar to that described in Example 1a).The residue obtained was purified by flash chromatography on silica,using as eluent an 8:2 hexane/ethyl acetate mixture to give1-(3-nitro-9H-carbazol-)acetone (4.5 g), which product was used withoutfurther purification for the subsequent reaction.

¹H NMR (300 MHz, DMSO-d₆) δ 9.20 (d, J=2.34 Hz, 1H), 8.42 (d, J=7.89 Hz,1H), 8.33 (dd, J=2.34, 9.06 Hz, 1H), 7.70 (d, J=9.35 Hz, 1H), 7.60-7.67(m, 1H), 7.54 (td, J=1.17, 7.75 Hz, 1H), 7.30-7.39 (m, 1H), 5.57 (s,2H), 2.32 (s, 3H).

d) 1-(3-amino-9H-carbazol-)acetone hydrochloride

To a suspension of the product obtained in the preceding step c) (1.3 g;0.005 mol) in 95° ethanol (80 ml) was added 10% Pd/C (0.5 g; 0.0005 mol)and the mixture was subjected to hydrogenation in a Parr hydrogenator(30 psi) for 4 hours. The reaction mixture was filtered and the solutionwas evaporated under reduced pressure. The product obtained wasdissolved in ethyl acetate and converted into the correspondinghydrochloride by adding ethanolic 5M hydrogen chloride solution. Thesolid precipitated out was filtered off to give1-(3-amino-9H-carbazol-)acetone hydrochloride (1.1 g).

¹H NMR (300 MHz, DMSO-d₆) δ 10.39 (broad s, 3H), 8.19 (d, J=7.60 Hz,1H), 8.14 (d, J=1.98 Hz, 1H), 7.62 (d, J=8.59 Hz, 1H), 7.52-7.58 (m,1H), 7.40-7.52 (m, 2H), 7.25 (ddd, J=0.99, 6.94, 7.93 Hz, 1H), 5.46 (s,2H), 2.27 (s, 3H).

e) N-[9-(2-oxopropyl)-9H-carbazol-3-yl]-2-(trifluoromethyl)benzamide

The product obtained in the preceding step d) (1.1 g; 0.004 mol) wasreacted by working in a manner similar to that described in Example 1c).

The solid obtained was crystallized from an isopropyl ether/isopropanolmixture (1:1) to giveN-[9-(2-oxopropyl)-9H-carbazol-3-yl]-2-(trifluoromethyl)benzamide (1.2g).

m.p.: 223-226° C.

Elemental analysis for C₂₃H₁₇F₃N₂O₂

C H N Found % 67.02 3.91 6.78 Calculated % 67.31 4.18 6.83

¹H NMR (300 MHz, DMSO-d₆) δ 10.52 (s, 1H), 8.50 (d, J=1.75 Hz, 1H), 8.10(d, J=7.60 Hz, 1H), 7.66-7.91 (m, 4H), 7.61 (dd, J=2.05, 8.77 Hz, 1H),7.36-7.53 (m, 3H), 7.20 (t, J=6.87 Hz, 1H), 5.38 (s, 2H), 2.24 (s, 3H).

EXAMPLE 5 Preparation of Compound 5 R1=Cl, R2=CH₂CH₂OH a)2-chloro-N-[9-(2-hydroxyethyl)-9H-carbazol-3-yl]benzamide

The product obtained as described in Example 1 b) (6.4 g; 0.028 mol) wassuspended in dichloromethane (70 ml). Triethylamine (7.9 ml; 0.2 mol)and 2-chlorobenzoyl chloride (3.95 ml; 0.031 mol) were then added to thesolution. The mixture thus obtained was stirred at room temperature for16 hours.

The solvent was evaporated off under reduced pressure, the residue wastaken up in 2N NaOH solution (80 ml), and the resulting solution wasrefluxed for 2 hours. The suspension thus obtained was poured intowater, and the product filtered off, dried and crystallized from 95°ethanol.

2-Chloro-N-[9-(2-hydroxyethyl)-9H-carbazol-3-yl]benzamide (5.5 g) wasthus obtained.

m.p.: 168-169° C.

Elemental analysis for C₂₁H₁₇ClN₂O₂

C H N Found % 68.83 4.63 7.58 Calculated % 69.14 4.70 7.68

¹H NMR (300 MHz, DMSO-d₆) δ 10.47 (s, 1H), 8.55 (d, J=1.98 Hz, 1H), 8.08(d, J=7.27 Hz, 1H), 7.39-7.71 (m, 8H), 7.18 (t, J=7.43 Hz, 1H), 4.86 (t,J=5.45 Hz, 1H), 4.43 (t, J=5.78 Hz, 2H), 3.78 (q, J=5.83 Hz, 2H).

EXAMPLE 6 Preparation of Compound 6 R1=Cl, R2=CH₂CH₂C(CH₃)₂OH a)2-chloro-N-[9-(3-hydroxy-3-methylbutyl)-9H-carbazol-3-yl]benzamide

The product obtained as described in Example 3d) (1.1 g; 0.0037 mol) wasreacted with 2-chlorobenzoyl chloride (0.52 ml; 0.0041 mol), by workingin a manner similar to that described in Example 1c).

The solid obtained was crystallized from ethyl acetate to give2-chloro-N-[9-(3-hydroxy-3-methylbutyl)-9H-carbazol-3-yl]benzamide (0.63g).

m.p.: 120-124° C.

Elemental analysis for C₂₄H₂₃ClN₂O₂

C H N Found % 70.52 5.62 6.71 Calculated % 70.84 5.70 6.88

¹H NMR (300 MHz, DMSO-d₆) δ 10.48 (s, 1H), 8.57 (d, J=1.98 Hz, 1H), 8.09(d, J=7.60 Hz, 1H), 7.41-7.73 (m, 8H), 7.19 (t, J=7.43 Hz, 1H), 4.55 (s,1H), 4.37-4.51 (m, 2H), 1.73-1.88 (m, 2H), 1.23 (s, 6H).

EXAMPLE 7 Preparation of Comparative Compound a

Comparative compound A corresponds to compound 1 of patent applicationWO 2006/122 680 and was prepared as described in the said patentapplication.

EXAMPLE 8 Preparation of Comparative Compound B

Comparative compound B corresponds to compound 6 of patent applicationWO 2007/014 687 and was prepared as described in the said patentapplication.

EXAMPLE 9 Preparation of Comparative Compound C

Comparative compound C corresponds to compound 13 of patent applicationWO 2007/014 687 and was prepared as described in the said patentapplication.

EXAMPLE 10 Test of In Vitro Activity

This test allows evaluation of the inhibitory capacity on the productionof the PGE₂ and the selectivity relative to the production of thePGF_(2α).

The cell line A549, human pulmonary adenocarcinoma, was used, which isparticularly sensitive to stimulation with pro-inflammatory cytokines,for instance IL-1_(β), and, in response to this stimulation, isparticularly active in the production and release of two prostanoids:PGE₂ and PGF_(2α) (Thoren S. Jakobsson P-J, 2000).

The cells were stimulated with IL-1_(β) (1 ng/ml) and simultaneouslytreated with the test compound for 22 hours in an appropriate culturemedium (DMEM—Dulbecco's Modified Eagle's Medium) supplemented with 5%foetal calf serum and L-glutamine (4 mM final) in an incubator at 37° C.and at a CO₂ concentration of 5%.

After the incubation, the amount of PGE₂ and PGF_(2α) produced andreleased into the supernatant were assayed using an EIA kit (producedand sold by Cayman Chemicals, Ann Arbor, Mich., USA).

The comparative compound used was indomethacin at a concentration of 10nM (Sigma-Aldrich), a non-steroidal anti-inflammatory drug that inhibitsin equal measure both PGE₂ and PGF_(2α).

The results, expressed as the IC₅₀ values, i.e. as the concentration ofcompound that inhibits 50% of the production of PGE₂ and of PGF_(2a)relative to the cells that have been stimulated, but not treated withthe same compound, are given in Table 2. The inactivity or the reducedactivity of the compound on the biosynthesis of PGF_(2α) is anindication of selectivity towards the production of PGE₂ and thus ofselective inhibition of mPGES-1.

TABLE 2 IC₅₀ [μM] Compound PGE₂ PGF_(2α) 1 2.9 >100 2 2.3 >100 31.4 >100 4 5.6 >100 6 0.6 >100 Indomethacin 0.005 0.003

EXAMPLE 11 Test of In Vivo Activity

The test compound was evaluated in the model of acetic acid-inducedwrithing in mice (Stock J. L. et al., J. Clin. Inv. 2001, 107: 325-331).This test allows evaluation of the antinociceptive activity of thecompounds of the invention in a model of inflammatory pain.

Female CD-1 mice weighing 25-30 g were used for the test. The animalswere treated intraperitoneally with the test compound (0.1-10 mg/kg)suspended in methylcellulose (MTC). The control animals were treatedwith the vehicle alone (MTC) via the same route.

Half an hour after the treatment, an intraperitoneal injection of aceticacid (0.7% v/v in physiological saline, 16 μl/g of body weight) wasgiven to the animals to induce inflammatory pain and to check theeffects of the test compound on the nociceptive response.

Immediately after the administration of acetic acid and for thefollowing 20 minutes the number of writhes was measured, whichrepresents the parameter for evaluation of the nociceptive response.

As shown in Table 3, the compound of the invention induced in adose-dependent manner a reduction in the number of writhes in the 20minutes following the administration of acetic acid, compared with theanimals treated with MTC alone.

TABLE 3 Treatment Dose (mg/kg) No. of writhes % of inhibition Vehicle —48.4 ± 3.66 — Compound 1 0.1 38.4 ± 3.99 21 1 31.5 ± 5.72 35 10 12.8 ±2.46 74

EXAMPLE 12 Test of Metabolic Stability in Human and Rat HepaticMicrosomes

This test allows evaluation of the metabolic stability of the compoundsof the invention and of the comparative compounds in rats and in man.

The test compounds were incubated in human hepatic microsomes (donorpool, Xenotech) and in hepatic microsomes from Sprague-Dawley rats(donor pool, Xenotech) and the comparison of the test compound wasmeasured so as to have an estimate of the metabolic stability in variousspecies using HPLC/MS/MS with an Applied Biosystems 4000 QTrap massspectrometer.

The compounds to be analysed, at a final concentration of 0 and 1 μM,were placed in a suspension containing the pool of microsomes at a finalconcentration of 0.5 mg/mL in a final volume of 200 μL, in 96-wellplates. The test was standardized with phosphate buffer (75 mM, pH 7.4)and with the NADPH regenerating system (MgCl₂: 3.3 mM; G6P: 3.3 mM;G6PD: 0.4 U/mL; NADP+: 1.3 mM). The reference compounds warfarin,propranolol and testosterone (Sigma) were incubated as a cocktail andtreated as for the test compounds. The samples were incubated at 37° C.in a humidified incubator. At time 0 and after 60 minutes, 100 μL ofacetonitrile containing the internal standard (0.2 μM of metoprolol and0.4 μM of diclofenac) were added to stop the reaction.

The samples were centrifuged before analysis. The HPLC/MS/MS analysiswas performed using an electrospray ion source in positive ionizationand SRM (Single Reaction Mode). The chromatographic conditions entailthe use of an XDB-C18 column (2.1×50 mm, Agilent) and a gradient from 5%to 91% of acetonitrile in water containing 0.1% formic acid (totalruntime equal to 6 minutes); the flow rate was 0.5 ml/minute.

The areas of the peaks for the test compounds were integrated and theresults expressed as the analyte area/internal standard (PAR) arearatio. For each time, two samples were analysed and the mean valuecalculated. The percentage of the value of remaining compound wascalculated as:% unmetabolized compound=100*(mean PAR_(Tfinal)/mean PAR_(T0)).

The results for compounds 1 to 6 are given in Table 4, together with theresults for the comparative compounds A, B and C and for the referencecompounds. The compounds of the present invention showed improvedmetabolic stability relative to the comparative compounds.

TABLE 4 Compound Rat Man 1 58% 81% 2 68% 82% 3 65% 77% 4 58%  7% 5 63%76% 6 74% 65% A 0.2%  51% B 0.4%  55% C 4.0%  22% Warfarin 97% 103% Propranolol 0.4%  66% Testosterone  0% 27%

EXAMPLE 13 Test of In Vitro Absorption

This test allows evaluation of the amount absorbed by the intestinalbarrier of the compounds of the invention and of the comparativecompounds using the Caco-2 cell line as an in vitro model of intestinalbarrier. The permeability test on Caco-2 cells represents an in vitrosystem approved for predicting and estimating the in vivo intestinalabsorption of a drug. When the Caco-2 cells are cultured on a porousfilter for about 21 days, they have the capacity to differentiate intoenterocytes. In practice, during this period, the Caco-2 cells undergospontaneous morphological and biochemical changes that result in theformation of a polarized cellular monolayer which has on the apicalsurface a well-defined “brush border” and form “tight junctions” betweenthe cells, thus representing a suitable model for analysis of theintestinal permeability of drugs.

The following materials were used to perform the test:

Lucifer yellow (Sigma)

Hank's balanced saline solution (HBSS) (Invitrogen)

radioactive reference standard (Perkin Elmer)

Caco-2 cells (ATCC)

Caco-2 MultiScreen™ plates (Millipore)

HPLC/MS/MS with Applied Biosystems 4000 QTrap mass spectrometer

Acetonitrile containing 0.2 μM of metoprolol as internal standard.

The compounds undergoing the test were diluted from a 10 mM stocksolution in HBSS to a final concentration of 10 μM. The system consistedof a confluent cellular monolayer in culture for 21-28 days. Thereference compounds (Lucifer yellow, atenolol, propranolol and digoxin)were included in each test as quality controls and for comparison withthe compounds undergoing the test.

Each compound was tested in triplicate, bidirectionally, at pH 7.4, fromthe apical to the basolateral compartment (A→B) and from the basolateralto the apical compartment (B→A).

The samples collected at the given time were analysed by HPLC-MS/MS,using an electrospray ion source in positive ionization and SRM (SingleReaction Mode). The chromatographic conditions entailed the use of anXDB-C18 column (2.1×50 mm, Agilent) with a gradient from 5% to 91% ofacetonitrile in water containing 0.1% formic acid (total runtime equalto 6.5 minutes) and a flow rate of 0.5 ml/minute. Metoprolol was used asthe internal standard.

The concentration data were used to calculate the apparent permeabilityvalues (P_(app)), and the mean and standard deviation of the P_(app)were calculated.

The flux ratio was calculated as P_(app)(B→A)/P_(app)(A→B). The recoverypercentage was calculated as:(amount in the receiving compartment+amount in the donorcompartment)/nominal amount

The area of the peaks of the test compounds were integrated and theresults were expressed as the analyte area/internal standard area ratioand corrected for the dilution factor used during the preparation of thesample. The apparent permeability coefficients were calculated using thefollowing equation:

$P_{app} = {\left( \frac{V_{A}}{{Area} \times {Time}} \right) \times \left( \frac{\lbrack{product}\rbrack_{receiving}}{\lbrack{product}\rbrack_{donor}} \right)}$

in which:

-   -   V_(A) volume in the receiving well (0.25 mL for the test from        A→B, 0.075 mL for the test from B→A)    -   Area area of the membrane surface (0.11 cm²)    -   Time total transport time (3600 seconds)

The values obtained were classified on the basis of the followingevaluation criterion.

-   -   Low P_(app)<2×10⁻⁶ cm/sec    -   Medium 2×10⁻⁶ cm/sec<P_(app)<20×10⁻⁶ cm/sec    -   High P_(app)>20×10⁻⁶ cm/sec

The results for compounds 1 to 6 are given in Table 4, together with theresults for the comparative compounds A, B and C and for the referencecompounds. The compounds of the present invention showed improvedexpectation of absorption relative to the comparative compounds.

TABLE 5 Compound Absorption 1 High 2 High 3 High 4 High 5 High 6 High ALow B Low C Medium Lucifer yellow Low Atenolol Low Propranolol HighDigoxin Low

EXAMPLE 14 Test of In Vivo Bioavailability

This test allowed evaluation of the in vivo bioavailability of thecompounds of the invention, thus making it possible to evaluate andcompare the pharmacokinetic profile of the test compounds.

The tests were performed using the cassette method, i.e. byadministering orally several products simultaneously to the same animal,at a dose of 5 mg/kg. The products were suspended in methylcellulose(MTC). The treated animals were catheterized for the serial collectionof blood samples performed by means of an automatic sampling system. Theplasmatic concentrations of the products were measured by HPLC/MS/MS.The profiles of the plasmatic concentrations over time made it possibleto evaluate the relative bioavailability of the test products in termsof rate (t_(max) and C_(max)) and species (AUC). The slope of the curvein the end portion also allowed a comparative evaluation of the rate ofelimination of the compounds from the plasma, the slower the rate, thelower the slope. Three animals were treated for each combination ofcompounds. The compound that had a higher C_(max) and AUC and anexpected t_(max) relative to the others was selected since it showed agood rate of in vivo absorption.

The comparative product used was compound C, which showed limitedabsorption, whereas compounds 1, 2 and 3 of the present invention showedgood bioavailability characteristics.

The results, expressed as the C_(max), i.e. as the maximum concentrationof drug reached in the plasma, T_(max), i.e. the time required to reachthe maximum drug concentration in the plasma, and AUC₀₋₇, i.e. the areaunder the curve of the plasmatic concentrations of drug over time,measured in the first seven hours after administration, are given inTable 5.

TABLE 5 C_(max) AUC₀₋₇ Compound ng/ml T_(max) h ng/ml * h 1 1200 1.55754 2 984 4.3 5403 3 457 1.8 2668 C 165 1.7 751

The invention claimed is:
 1. A method for producing a 3-aminocarbazolecompound of formula (I):

wherein R1 is a halogen atom, a methyl group, a trihalomethyl group, anitro group, a cyano group, or a triflate group, and R2 is a linear orbranched hydroxyalkyl group having from 1 to 8 carbon atoms or a linearor branched carbonylalkyl group having from 1 to 8 carbon atoms, or apharmaceutically acceptable salt thereof, a polymorphic crystal formthereof, a stereoisomer thereof, an enantiomer thereof or a prodrugthereof, said method comprising: (a) reacting an amine of formula (II):

with a compound of formula (III):

wherein Z is selected from the group consisting of Cl, Br, OH, OR, andOC(O)R, wherein R is a linear or branched alkyl having from 1 to 6carbon atoms, to obtain a 3-aminocarbazole compound of formula (I)

and (b) optionally forming a pharmaceutically acceptable salt, apolymorphic crystal form, a stereoisomer or an enantiomer of saidcompound of formula (I), wherein said prodrug is an ester prodrug.
 2. Amethod according to claim 1, wherein R1 is a fluorine atom, a chlorineatom, a trifluoromethyl group, or a trichloromethyl group, and R2 is alinear or branched hydroxyalkyl group having from 1 to 6 carbon atoms ora linear or branched carbonylalkyl group having from 1 to 4 carbonatoms.
 3. A method according to claim 1, wherein: (i) R1 is CF₃ and R2is CH₂CH₂OH; (ii) R1 is CF₃ and R2 is CH₂C(CH₃)₂OH; (iii) R1 is CF₃ andR2 is CH₂CH₂C(CH₃)₂OH; (iv) R1 is CF₃ and R2 is CH₂COCH₃; (v) R1 is Cland R2 is CH₂CH₂OH; or (vi) R1 is Cl and R2 is CH₂CH₂C(CH₃)₂OH.